The Complicated Story Behind 18,000 Dead Penguin Chicks

This year, Adélies had to travel across more sea ice than usual to reach their feeding grounds.

Andrew Shiva via Wikimedia Commons

An enormous colony of Adélie penguins—around 40,000 of them—lives in eastern Antarctica. Scientists have been observing these flightless birds since the 1960s, and each year between January and March, those breeders get busy. The area becomes home to literally thousands of squawking fluff balls, otherwise known as penguin chicks. But this year, scientists encountered about 18,000 tiny gray corpses instead. All but two of the colony’s Adélie chicks had died, apparently of starvation.

The field scientists know life on this frigid continent can be brutal and unforgiving, but the sad scene still shocked them. Rod Downie, head of WWF’s polar program in the United Kingdom, likened the sight to a Quentin Tarantino remake of Happy Feet.

Believe it or not, this is the second penguin chick die-off for the east Antarctica population in recent history. During the breeding season of 2013–2014, not a single chick survived.

Thankfully, the Adélie penguin is not endangered. After the first global census of these birds was conducted in 2014, scientists estimated that nearly 3.8 million breeding pairs existed across Antarctica. And their numbers are actually increasing.

But surely 18,000 dead chicks should be something to keep an eye on. And the fact that there have been two such incidents in three years feels warning-flaggish, no?

Well, it’s complicated.

Life as an Adélie

Adélie penguin parents reproduce by laying a single egg on shore and taking turns keeping the egg (or chick) warm while the other waddles back to the sea to eat fish and krill. When the hunting parent returns, it feeds the chick and swaps places with its mate, which in turn makes its way back to the ocean for food. It’s a bizarre arrangement, but it works. Until it doesn’t.

Adélie penguins with their single eggs

Dr. Robert Ricker, NOAA/NOS/ORR

This year, for instance, the adults had to travel across more sea ice than usual to get to their feeding grounds. This may be a little confusing, because we’re always hearing about how global warming is melting too much sea ice. Just this March, in fact, NASA announced that sea ice coverage at both poles had hit the lowest levels ever been recorded since regular measurements began in 1979.

“The message has very much been that climate change equals global warming and that warming will be bad for all species,” says Heather Lynch, a quantitative ecologist at Stony Brook University who has studied Adélie penguin populations. “The truth of the matter is that climate change is complicated.”

Lynch says the planet’s changing climate will make some regions warmer while others get cooler. Similarly, one place may experience drought while another receives record levels of precipitation. In Antarctica, changes in temperature, wind patterns, and water currents have created areas with more ice coverage than usual, even as other parts of the continent experience record lows.

But wait―it can get even more complicated down there. When an iceberg rammed into the Mertz Glacier in western Antarctica in 2010, the glacier’s icy “tongue” broke off and became a new iceberg. That might not seem significant, but this new hunk of floating ice is almost 50 miles long. An ice island that size can change water current patterns wherever it goes. This, in turn, can affect environmental conditions all over the continent—and in ways we’re only beginning to understand.

Because there are still so many unknowns and variables swirling around this frozen or semifrozen landscape, Lynch cautions against pegging the penguin deaths to any one factor at this point.

“I think we have to be super cautious as a community in interpreting these changes,” she says. As for all the dead chicks, well, Lynch says it’s an interesting data point. “Whether or not that’s a call to action, I’m a bit more skeptical on that.”

Death Is Life for an Adélie

One of the reasons the recent body count doesn’t move Lynch is because dying is just something Adélie chicks do.

Murray Foubister/Flickr

“Most will never survive to reproduce,” she says. In fact, a scenario in which 70 percent to 80 percent of chicks never reach their first birthday is fairly common. What’s more, when breeding conditions aren’t good, adult Adélies sometimes take the year off. Therefore, a 100 percent loss of chicks one year won’t necessarily make a dent in the population over the long term.

“None of this is to say it’s not a big deal,” says Michelle LaRue, a research ecologist at the University of Minnesota who has worked with Lynch assessing penguin populations by satellite and conducting that first Adélie penguin census back in 2014. “But in the grand scheme of things, there are millions and millions of these birds.” LaRue says the occurrence highlights the fact that we need more research to understand what’s going on at the bottom of the world. “That’s not meant to be obtuse. It’s true!” Antarctica, after all, is harder than most places to study.

Lynch explains that the satellites typically used to measure precipitation don’t usually go as far south as they need to, nor are they very good at distinguishing clouds from snow and ice. What’s more, she says, the wind blows the snow around so much that it’s tough to understand how much has fallen. And when it rains in Antarctica, it tends to fall sideways due to high winds, making collecting water for rainfall measurements far more difficult.

All of these weather patterns are crucial to understanding how the Adélie penguins will fare in any given season. One major rain event is enough to flood the penguins’ nests and kill eggs or freeze chicks to death, since they lack waterproof feathers. “Just a couple degrees difference between snow and rain literally is life and death for a young chick, and it’s something that we have almost no handle on whatsoever,” says Lynch.

Finally, Adélie penguins are relatively long-lived seabirds, with maximum life spans approaching 20 years. This means we may have to wait another five to ten years before we’ll know if the recent unpleasantness has had a significant impact on the population at large.

In the meantime, we know climate change is still taking its toll on wildlife at the poles. Changing landscapes mean new niches for invasive species to exploit, more potential for oil and gas development (and the pollution that comes with it), and easier access for fishing industries that have already ravaged other seas. So even if the Adélies aren’t on climate change’s deadly tally today, the polar bears, the Arctic foxes, and the crabeater seals are.

onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.